Pulley-locking device



(No Model.)

Wi/lmeom,

W. H. KIRKMAN.

PULLEY LOOKING DEVICE.

Paten ted'Aug. 10, 1897.

UNITED STATES PATENT OFFICE.

\VILLIAM H. KIRKMAN, OF BERKELEY, CALIFORNIA, ASSIGNOR TO E. POEHLMAN, OF SAN FRANCISCO, CALIFORNIA.

PU LLEY-LOCKING DEVICE.

SPECIFICATION forming part of Letters Patent No. 587,976, dated August 10, 1897.

Application filed November 30, 1896. Serial No. 613,995. (No model.)

To all whom it 71mg concern:

Be it kn own that 1, WILLIAM H. KIRKMAN, a citizen of the United States, residing at Berkeley, county of Alameda, State of California, have invented an Improvement in Pulley-Locking Devices; and I hereby declare the following to be a full, clear, and exact description of the same.

My invention relates to a device whereby pulleys may be locked, so as to prevent the return of a cord or rope passing over the pulley by which the weight is being lifted or where in any case it is desired to prevent the return of the rope when released.

It consists in the combination, with a pulley having a central rope-groove and spirallydisposed side locking-grooves, of a spring-actuated shaft slidable through the pulley and a rope-guide carried by said shaft, so that when power is applied to pull upon the rope the rope will be carried into the central groove, so as to rotate the pulley and be movable thereon, and when the pull upon the rope is released it will be carried to one side, so as to follow the spiral locking-groove and be automatically looked as soon as released.

In the accompanying drawings, Figure 1 is a View showing the guide in position to lock the rope. Fig. 2 shows the rope in an unlocked condition.

This device' is applicable to any pulleys over which a rope is carried, and its operation may be well illustrated in connection with hoisting apparatus of any kind.

A is a pulley having a central groove a, over which the rope or cord B is adapted to pass, and b are spirally-disposed grooves leading from the central groove toward the periphery of the pulley.

The frame or block C, in which the pulley is journaled, is so constructed that there is space enough between the central groove of the pulley and the back of the frame to allow the rope to move easily when the rope is in the central groove of the pulley, and that portion of the frame upon each side of the central groove is so close to the periphery of the pulley that when the rope is carried into the spirally-disposed groove upon either side it will be caused to bind between the side of the pulley and the frame, this part of the device being well illustrated in the pulleys, which are employed in connection with spring-actuated roller-curtains which are journaled at the bottom of the window and are pulled up by a cord passing over a pulley of this description. The ordinary method of locking these pulleys is to raise the curtain to the desired height by pulling the cord centrally. The cord is then thrown over to one side and the pulley allowed to turn backward until the cord has passed into the spirally-disposed binding-groove.

Y The difficulty with this device is that if the cord slips out of the fingers or isaccidentally released without being thrown into the position to be locked the curtain or weight will immediately descend to the bottom without any check.

In my invention the pulley is journaled between the side plates 0, and the shaft D, upon which the pulley turns loosely, may also be loosely slidable through its bearings in the plates. 0, or, if preferred, the shaft may be fixed in its bearings and the yoke E may be slidable upon instead of with the shaft. The shaft extends to a considerable distance outside of these plates and carries the yoke E. A-sprin g F, of any suitable or desired description, or an equivalent weight acts to force the yoke constantly to one side. Through the front of the yoke is made a hole G of sufficient size to allow a rope or cord which passes over the pulley to lead freely. The action of the spring or weight maintains this opening normally opposite one side of the pulley, so that the rope or cord will be caused to run into one of the spiral grooves when released and thus be looked, as previously described. W'hen the rope or cord is pulled for the purpose of raising the weight connected with the opposite end, the first action will. be to pull the yoke so that the opening G is opposite the center of the pulley, the spring or weight yielding to allow this movement. ing being in this position it will be seen that the rope Will run freely over the pulley and The openv Lil the weight attached to the opposite end can be raised to any desired point. As soon as the rope or cord is released the action of the spring or weight will throw the yoke to one side, carrying that portion of the rope which passes through the hole with it, so that the cord or rope will immediately follow the spiral groove of the pulley and become locked. It will thus be seen that the locking of the cord or rope becomes automatic, and if it is accidentally released While the hoisting is going on it'will be immediately locked and prevented from returning.

It will be manifest that this device may be applied to Window-curtains such as previously described and also to hoisting apparatus of larger dimensions.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, ise 1. The combination, with a grooved pulley having spiral lockingchannels, of a shaft slidable through the pulley,-bearings for said shaft, ahoisting cord or line, a yoke connected with the shaft having an opening through which the hoisting cord-or rope passes from the pulley, a spring whereby the yoke is normally moved to one side with the openingout of line with the pulley-groove, said spring yielding to allow the rope to move, sothat the rope is brought into line with the pulleygroove when power is applied.

2. A pulley-locking device consisting of a yoke connected with the ends of the pulleyshaft, said yoke having a central opening adapted to be brought into line with the groove of the pulley or moved to one side thereof, a. pulley loosely journaled upon the shaft, bearings between which the pulley is mounted and within which the shaft, is slidablelongitudinally, a holding cord or rope and'a means whereby the yoke is normally drawn to one side so as to bring the cord or rope which passes over it and through the yoke-opening,

into position to be locked against the pulley- 

